October Birthstone

Opal is the older traditional October birthstone, with deep roots in Australian and ancient European jewellery. Tourmaline was added later to give October-born wearers a more durable everyday option, and both are recognised today.

Opal contains 3 to 21 per cent water, and its play of colour comes from light diffracting through microscopic silica spheres. Australian black opal, white opal and crystal opal are graded by the strength and pattern of that colour play. Tourmaline gets its colour from a long list of trace elements, and a single crystal can carry several colours at once: watermelon tourmaline shows green and pink in the same stone. Opal has long stood for creativity and imagination, and tourmaline for grounded protection.

Opal is softer at 5.5 to 6.5 Mohs and contains water, so it can crack or craze with sudden temperature changes and shows wear faster than harder stones. A protected setting is strongly preferred for an opal ring. Tourmaline at 7 to 7.5 Mohs is much more practical for rings worn every day and is the easier of the two October stones to live with.

Australia produces over 90 per cent of the world black, white and crystal opal, with Lightning Ridge famous for black opal and Coober Pedy for white. Pliny the Elder wrote that opal contains the colours of every other gem. Tourmaline arrived in Europe through Dutch traders in the 1700s and its colour range was only fully classified in the 19th century. Paraiba tourmaline, with its neon turquoise-blue colour, was discovered in Brazil only in 1989.

For October, an Australian opal pendant in yellow gold makes a striking and uniquely Australian gift. Opal earrings are a safer everyday choice than a ring face. For an engagement-style piece, a rubellite or pink tourmaline in a halo setting gives strong colour and good durability. Watermelon tourmaline slices, with both pink and green visible in a single stone, make distinctive pendants.

Opal needs gentle care. Never use ultrasonic or steam cleaners. Clean with a soft damp cloth, avoid extreme temperature changes and very dry environments, and store away from harder stones. Tourmaline is easier: warm soapy water, soft brush, and most stones are safe for ultrasonic cleaning.